Modified Files: billCalendar.rb, firstDMY.rb, billWk.rb

Breakdown of Changes:
	billWk.rb:
		Renamed instance variables "firstDay", "lastDay" to "billWk_firstDay" and "billWk_lastDay".
		Also changed Class name "BillWk" to "BillWK" notice the capitialization of the letter "K".

	firstDMY.rb:
		Renamed instance variables "day", "month", "year" to "init_day", "init_month", "init_year".

	billCalendar:
		Changing how BillCalendar class is initialized.  Previously initial variables were hidden
		from entire class.  That may be a pain in the future to maintain so will be using hash
		arguments.

		Note:
		BillCalendar is dependent on billWk and firstDMY objects.

		*  billWk = billWk_firstDay and billWk_lastDay (firstDay and lastDay of a billWeek)
		*  firstDMY = init_day, init_month, init_year (initial bill date of the calendar)